Filter for water-taking wells

ABSTRACT

A filter for water wells comprises a casing mounted on an apertured inner frame, the casing having conical or pyramidal external projections, the top of each projection being provided with a hole for water passage. The edges of the holes in the projections are sharp pointed and of different height to promote formation of cavities in the surrounding soil at the holes during pumping of water.

United States Patent Kulikov et al.

[54] FILTER FOR WATER-TAKING WELLS [22] Filed: Jan. 30, 1970 [21] Appl.No.: 7,105

[ 1 July 25,1972

[56] References Cited UNITED STATES PATENTS 342,667 5/1886 Wiser 166/236 405,199 6/1889 Chapman.....- ..166/227 X 1,500,828 7/1924 Layne ..166/236 1,731,366 10/1929 Windsor 166/227 X 3,330,361 7/1967 McCullough ..l66/227 3,366,188 1/1968 Hicks l75/4.6 3,431,975 3/1969 Blake ..166/227 Primary Examiner-David H. Brown Attorney-Waters, Roditi, Schwartz 8L Nissen ABSTRACT A filter for water wells comprises a casing mounted on an apertured inner frame, the casing having conical or pyramidal external projections, the top of each projection being provided with a hole for water passage. The edges of the holes in the projections are sharp pointed and of difi'erent height to promote formation of cavities in the surrounding soil at the holes during pumping of water.

6 Claims, 2 Drawing Figures 52] user ...1 66/236,166/227 511 lnt.Cl ..E21b43/08 5s FieldofSearch ..166/227,229,233,235,236; 175/46 Patantad July 25, 1972 FILTER FOR WATER-TAKING WELLS The present invention relates to a filter for waterwells which filter has a casing provided with a plurality of external projections, each having a hole for passage of water.

This filter can be used for water removal from deep wells sunk in fine-grained, medium-grained and rough-grained sands of water-bearing strata for the purpose of water supply, preliminary drainage and hydrological surveys.

Filters of this type are normally arranged within the wells on a string of pipes within the zone of the water-bearing stratum. Those skilled'in the art know that filters of various designs are employed for deep-well pumping of water.

In one case for removal the water from large-grained and medium-grained sands, the filters have outer projections (bridgers) pressed out from the casing and provided with lateral slots for passage of water. In another case, this casing is made in the form of a grid, a porous ceramic or a coiled wire having a gap between the coils for passage of water.

Employed for removal of water from fine-grained sands are filters having the same construction but provided with a gravel filler around the filter introduced into the well within the zone of the water-bearing stratum. The known filters cannot be operated without the gravel filler in fine-grained sands due to the fact that some (grid-type, of porous ceramic) are quickly clogged with sand, while other ones (slotted) continuously admit sand into the well.

However, the gravel filler can be provided only in largediameter productive wells having a comparatively small depth, and this operation requires a considerable amount of work and is expensive.

Therefore, the known filters are not suitable for removal of water from small-diameter and deep wells. Furthermore, the known filters with a gravel filler are not reliable in operation because the sand penetrates into the well through passages formed in the gravel filler, while detection and elimination of these faulty places are extremely difficult.

The main object of the present invention is to provide a filter for removal of water from wells in fine-grained sands without the use of a gravel filler.

Another object of the invention is to provide a filter which is simple in construction and reliable in operation.

A specific object of the invention is to provide a filter having such a shape of the projections on its casing and such an arrangement of holes therein which make it possible to use the filter in water wells sunk to the level of fine-grained sands without the use of a gravel filler and to provide an efficient operation of this filter.

According to the present invention, the projections on the casing widen at their bases, while the holes for passage of water are provided in the tops of these projections.

It is expedient that the projections be of conical or pyramidal shape and have a height not less than 3 mm from the external surface of the casing.

In the process of pumping the water through the filter, these projections contribute to the formation of comparatively stable caverns or cavities due to removal of a portion of the sand near the holes, these caverns being separated one from another. In this case the carry-away of the sand is stopped as soon as the total surface area of these caverns (the area of water-taking) is approximately equal to the total surface of the filter.

In this period there is provided a hydrodynamic balance of the forces carryingthe sand and the forces of the hydrostatic pressure of the water head in the well.

It is also expedient that the holes in each projection have uneven sharp-pointed edges, and the distance between the holes of the adjacent projections is not less than 10 mm.

The uneven edges of the hole help to increase the stability of the formed caverns.

The invention is advantageous in that the proposed filter Another advantage of the invention consists in the simplicity and efficiency of the proposed filter.

Still another advantage of the invention consists in a stable operation'of the filter in fine-grained sands without clogging and in the possibility of using this filter in wells drilled with a clay mortar without preliminary declaying of such wells (removal of the clay from the wells). Other objects and advantages of the invention will be apparent from the following description of a preferable embodiment of the invention taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a longitudinal view, proposed filter; and

FIG. 2 is an enlarged sectional view of a portion of the casing of the filter and the caverns formed near the holes of the projections.

As shown in FIG. 1 the proposed filter has a casing 1 with external projections 2 of a conical or pyramidal shape and a height not less than 3 mm from the outer surface of the casing. The projections are provided with holes 3 in the top for passage of water, these holes having a cross section up to 1.5-2 sq.mm. In this case the distance between the holes 3 of the adjacent projections 2 is not less than 10 mm.

If the filters are assembled into an elongated column or in deep wells, the casing l is attached to a frame 4 in the form of a metal or asbestos-cement tube with openings 5 for passage partly in section, of the of water. The casing l is attached to the frame 4 by means of I rings 6 whose diameter exceeds the diameter of the filter, taking into account the projections 2, to prevent them from mechanical damage when lowering the filter into the well. The

. ends of the frame 4 have a thread 7 for connecting separate provides for an increase of the yield of the well and obviates sections into a column and for attaching it to the string of tubes (not shown) on which the filter is lowered into the well.

' As shown in FIG. 2, during pumping of the water, separate caverns 8 are formed in the sand near the tops of the projections 2. The edges of the holes 3 of the projections have sharp points of different height which contribute to reinforcement of the base of the caverns 8 as in the action of roots of plants binding the soil. v

The operation of the proposed filter may be compared with that of wells without filters featured by stable walls which do not cave-in during the movement of water. In fact, during the operation of the proposed filter, the sand is carried into the well only in the period of prepumping the well up to the moment of clarification of the water when the above-described caverns are formed; after that the delivery of sand into the well is stopped.

On setting the filter into a well, it is assembled in strings by means of conventional connecting members (threaded or flanged).

Industrial-scale tests have shown that the proposed filters can be effectively used in wells cut with the use of clay mortar and do not require preliminary declaying of these wells.

During the operation of the filter in water-bearing strata which for -98 percent consist of fractions of sand sized 0.25 to 0.001 mm at a diameter of the well of up to 108-146 mm, a yield of water has been obtained rated from 50 to cu.m per hour, and this exceeds the yield of wells equipped with the known strainers by a factor of S to 7. In other cases the filter has been used for removal of mineral water from fine-grained sands in wells of up to 1,000 m deep, in which case a high yield (up to 50 cu.m per hour) at a diameter of the filter of 89-108 mm has also been obtained.

In all cases the delivery of sand into the well was quickly terminated and this allowed reduction of the time necessary for pumping the well.

Furthermore, the proposed strainer has been used many times.

The proposed filter can easily be made in shops servicing the boring works as no complicated equipment is necessary for manufacturing such a filter.

We claim:

l. A filter for water wells comprising an inner frame with openings for passage of water, and an outer casing mounted on said frame and including a plurality of external projections distributed thereon, said projections being of generally conical shape extending outwardly in narrowing manner from said casing, each said projection having an outermost end with a substantially circular hole therein for passage of water through the casing and the inner frame,said projections having edges at said holes which are sharp pointed to promote formation of cavities in the surrounding soil at said holes during pumping of water.

2. A filter as claimed in claim 1 wherein said edges at said holes are of different height.

3. A filter as claimed in claim 2 wherein said sharp pointed edges are formed directly in the material of the projections.

4. A filter as claimed in claim 3 wherein said edges are formed by ridges and crests in the material of the projections.

5. A filter as claimed in claim 4 comprising rings on said inner frame securing said outer casing to the frame, said rings projecting to a height from the inner frame which exceeds the height of the projections from said inner frame to protect the projections during insertion of the filter into a well.

6. A filter as claimed in claim 5 wherein said projections have a projection height exceeding 3 mm from the external surface of the casing. 

1. A filter for water wells comprising an inner frame with openings for passage of water, and an outer casing mounted on said frame and including a plurality of external projections distributed thereon, said projections being of generally conical shape extending outwardly in narrowing manner from said casing, each said projection having an outermost end with a substantially circular hole therein for passage of water through the casing and the inner frame, said projections having edges at said holes which are sharp pointed to promote formation of cavities in the surrounding soil at said holes during pumping of water.
 2. A filter as claimed in claim 1 wherein said edges at said holes are of different height.
 3. A filter as claimed in claim 2 wherein said sharp pointed edges are formed directly in the material of the projections.
 4. A filter as claimed in claim 3 wherein said edges are formed by ridges and crests in the material of the projections.
 5. A filter as claimed in claim 4 comprising rings on said inner frame securing said outer casing to the frame, said rings projecting to a height from the inner frame which exceeds the height of the projections from said inner frame to protect the projections during insertion of the filter into a well.
 6. A filter as claimed in claim 5 wherein said projections have a projection height exceeding 3 mm from the external surface of the casing. 